Hydrocarbon production system and method of use

ABSTRACT

The method of the present invention employs a subsurface production pump to displace hydrocarbon fluid, including any and all accompanying ground water and/or earthen contaminants, from the subterranean hydrocarbon reservoir depth of an oil well to surface storage and handling facilities via the subsurface production tubing, wellhead and surface flow line. As the subsurface production pump operates, compressed gas, or a mixture of compressed gases of sufficient volume and force is fed into the lower end of the subsurface production tubing in proximity to, or at a point above the subsurface production pump to mix into the hydrocarbon production fluid column. The resultant and considerably reduced density of the subsurface hydrocarbon production fluid column provides a reduction of subsurface production pump loading with all types of subsurface production pumps, and an improvement of sucker rod fall time when sucker rod activated subsurface plunger pumps are employed. Due to the additional cubic volume of the injected compressed gas, the increased hydrocarbon production fluid and gas velocity within the subsurface production tubing and the surface flow line improves hydrocarbon fluid shear from the conduit walls and sucker rod surfaces, and prevents earthen contaminants such as sand, clay, shale, coal or other rock fragments, from precipitating, accumulating and blocking the flow of hydrocarbon production fluid within the subsurface production tubing and the surface flow line.

BACKGROUND OF THE INVENTION

The purpose of the present invention is to provide an improved method and an improved apparatus to displace light, medium, heavy or very viscose hydrocarbon fluid which may be contaminated with earthen solids and water, from a subterranean hydrocarbon reservoir to a hydrocarbon production fluid storage tank or other handling facilities on ground surface, by means of oil well production, especially in oil wells wherein currently used hydrocarbon production systems are mechanically incapable of sustained or economic production.

The method of the present invention employs a subsurface production pump to displace hydrocarbon fluid, including any and all accompanying ground water and/or earthen contaminants, from the subterranean hydrocarbon reservoir depth of an oil well to surface storage and handling facilities via the subsurface production tubing, wellhead and surface flow line. As the subsurface production pump operates, compressed gas, or a mixture of compressed gases of sufficient volume and force is fed into the lower end of the subsurface production tubing in proximity to, or at a point above the subsurface production pump to mix into the hydrocarbon production fluid column.

The resultant and considerably reduced density of the subsurface hydrocarbon production fluid column provides a reduction of subsurface production pump loading with all types of subsurface production pumps, and an improvement of sucker rod fall time when sucker rod activated subsurface plunger pumps are employed. Due to the additional cubic volume of the injected compressed gas, the increased hydrocarbon production fluid and gas velocity within the subsurface production tubing and the surface flow line improves hydrocarbon fluid shear from the conduit walls and sucker rod surfaces, and prevents earthen contaminants such as sand, clay, shale, coal or other rock fragments, from precipitating, accumulating, and blocking the flow of hydrocarbon production fluid within the subsurface production tubing and the surface flow line.

DESCRIPTION OF PRIOR ART

Subterranean hydrocarbon reservoir characteristics and hydrocarbon fluid characteristics, may present problems wherein continuous or more economical hydrocarbon production is difficult or not possible while employing current production systems including subsurface sucker rod driven plunger pumps and progressive cavity pumps or other types of subsurface production pumps.

The more viscose hydrocarbons have a great tendency to adhere to inner conduit walls and sucker rod surfaces, and also have very resistant fluid flow shear properties. Relatively clean hydrocarbon fluids having a temperature of 20 degree Centigrade and densities of 980 to 999 kg per cubic meter, being pumped to surface from a 600 meter deep oil well, may require 60% more pumping horsepower than when pumping the same volume of light hydrocarbon fluid having the same temperature from similar depths.

Sucker rod activated tubing liner or insert type subsurface production pumps are the mainstay of most oil fields around the world, and are very well suited to the production of light and medium hydrocarbons and will often operate trouble free for several years. When used for the production of more viscose hydrocarbons such as heavy oil or bitumen, which may contain earthen contaminants, the sucker rods will often float on the downstroke and must be slowed down to prevent pump jack and/or sucker rod damage. Reduced daily production is thereby unavoidable.

If the light or viscose hydrocarbon fluid being produced contains considerable amounts of earthen particulates, the earthen particulates may accumulate and cause fluid blockages within the subsurface production tubing and surface flow line. When the accumulation of earthen particulates becomes too great, the sucker rods simply will not fall, or will not fall at an acceptable fall rate, through the column of hydrocarbon fluid and earthen materials, and production thereby fails, and well servicing is required. The earthen particulates also cause extreme abrasion of the sucker rods and production tubing and premature failure of each, which eventually will require replacement of each. Sucker rod and production tubing abrasion, wear and mechanical stress is greatly increased in oil wells that have high pumping pressures and/or deviations off the vertical line due to drilling problems, or in slant, whip stocked or horizontal well bores.

Progressing cavity subsurface production pumps driven by sucker rods are more successful in the production of the more viscose hydrocarbons and are, to a degree, somewhat better able to cope with earthen particulates. These pumps inherit all the problems associated with sucker rod use, are quickly destroyed when the well bore fluid is pumped off, or the rotors and stators will be badly damaged when pumping rock fragments or pyrite balls or sand or sand slugs. They have a much shortened life and a much reduced efficiency when pumping high fluid pressures and/or high fluid temperatures. They also have a much shortened life when pumping high amounts of earthen particulates, especially water sand and rock fragments. Within many oil sands production wells, seizure of the sucker rods by accumulations of earthen particulates packed within the subsurface production tubing string is a never ending problem that may occur daily. Electrically driven submersible progressing cavity pumps enjoy some use in the effort to eliminate friction and abrasion caused sucker rod and production tubing wear, but are still prone to the other limitations of progressing cavity pumps.

A great number of oil wells producing light or heavy oil or bitumen from earthen particulate laden subterranean hydrocarbon reservoirs, employing any of the subsurface production pumps available to-day, would be rendered technically or economically inoperable without the very expensive and frequent backup services of auxiliary equipment including pressure trucks, flush-by rigs, well servicing rigs or coiled tubing rigs to remove accumulated earthen particle build-up and/or blockages from the oil well's well bore, subsurface production pump, subsurface production tubing and surface flow line. Frequent replacement of subsurface components due to excessive metal to metal wear, especially in the presence of abrasive produced earthen particulates, presents considerable replacement cost in addition to the economic loss of sales revenue due to oil well down time.

A percentage of such oil wells present ongoing problems that seem unsolvable. After spending substantial amounts of time, money and fruitless effort, such oil wells are sooner or later considered to be mechanically or economically not viable, and are usually sold or abandoned.

SUMMARY OF THE INVENTION

More particularly, in accordance with one aspect of this invention, there is provided a subsurface production pump connected to the lower end of a compressed gas conveyance tubing system, with said compressed gas conveyance tubing system extending from a source of compressed gas at surface, down into and returning up out of an oil well having a subterranean hydrocarbon reservoir, oil well casing and casing perforations that provide hydrocarbon fluid inflow from the subsurface hydrocarbon reservoir into the well bore, the improvement comprising a compressed gas conveyance tubing system employing a subsurface production pump and including;

a source of compressed gas; a wellhead; conduit means to connect the source of compressed gas to the wellhead; a subsurface compressed gas feed tubing string extending from a connection at the wellhead to the approximate subsurface hydrocarbon reservoir depth of the well bore; a subsurface hydrocarbon production tubing string extending from the approximate subsurface hydrocarbon reservoir depth, through the wellhead to a surface flow line connection; a surface flow line with a connection at one end to the subsurface hydrocarbon production tubing string, and a connection at the other end to a hydrocarbon production fluid storage tank; a hydrocarbon production fluid storage tank or other fluid handling facility(s); means to vent gas from the hydrocarbon production fluid storage tank; a subsurface production pump connected to the lower subsurface end of the compressed gas conveyance tubing system; means for fluid communication from the subsurface production pump into the subsurface hydrocarbon production tubing string; means for gas communication from the subsurface compressed gas feed tubing string into the subsurface hydrocarbon production tubing string; means to recover hydrocarbon fluid and contaminants.

In another aspect of the present invention, there is provided an improvement in a method of displacing various grades of hydrocarbon fluid, which may be contaminated with earthen contaminants and ground water, from subterranean hydrocarbon reservoirs to surface storage, by means of oil well production, which method includes the steps of;

Flooding hydrocarbon fluid from the subterranean hydrocarbon reservoir into the well bore; pumping hydrocarbon production fluid and it's contaminants from the well bore, into and through the subsurface hydrocarbon production tubing string, through the wellhead, into and through the surface flow line, and into the hydrocarbon production fluid storage tank or other handling facility(s) at surface;

feeding compressed gas of sufficient volume and pressure from a source at surface, by conduit means, into and through the wellhead, into and through the subsurface compressed gas feed tubing string, into and through the compressed gas communication port, into and through the subsurface hydrocarbon production tubing string, through the wellhead, into and through the surface flow line, and into the hydrocarbon production fluid storage tank or other handling facility(s) at surface; mixing compressed gas, hydrocarbon fluid and it's contaminants within the subsurface hydrocarbon production tubing string; permitting the compressed gas to decompress within the subsurface hydrocarbon production tubing string and surface flow line; providing a means to separate produced hydrocarbon fluid and gas at surface; venting gas from within the hydrocarbon production fluid storage tank or other handling facility(s) at surface; providing means to recover hydrocarbon fluid and contaminants from the hydrocarbon production storage tank or other handling facility(s) at surface; continuing the production cycle.

In the present system and method, any suitable subsurface production pump including progressing cavity pumps, plunger pumps or electric submersible pumps, may be used to pump grades of light to very viscose hydrocarbon fluid which may contain substantial amounts of solid earthen contaminants and/or ground water, from the well bore into the hydrocarbon production storage tank or other handling facility(s) at surface.

Use is made of the fact that a compressed gas feed of sufficient volume and pressure can be injected into the lower end of the subsurface production tubing string in order to provide certain mechanical effects and advantages throughout the entire hydrocarbon pumping apparatus.

As the compressed gas is fed into the lower end of the subsurface hydrocarbon production tubing string at a point preferably, but not necessarily, located just above the operating subsurface production pump, the preferably continuous feed of compressed gas is mixed and combined with hydrocarbon production fluid. As the mixture advances upwards to the surface storage facility(s) at an accelerated fluid velocity due to the additional volume of injected gas, the gas decompresses proportionally, throughout the entire subsurface hydrocarbon production fluid column, resulting in a subsurface hydrocarbon production fluid column of much lighter weight or density above the subsurface production pump, the advantages being a considerably reduced load on the subsurface production pump, reduced mechanical strain and wear on all components throughout the entire pumping apparatus, and an increased hydrocarbon production fluid velocity within the subsurface hydrocarbon production tubing string and surface flow line. The higher fluid velocity improves viscose fluid flow properties through conduits and improves the fluid flow entrainment of solids though conduits. If sucker rod driven subsurface plunger pumps are used, sucker rod fall time is very much reduced due the much reduced density of the hydrocarbon production fluid column, and less horsepower is required to lift the sucker rods during the upstroke. If sucker rod driven progressing cavity pumps are used, considerably less horse power is required to drive the sucker rod string due to the reduced work load on the progressing cavity pump, and there will be a considerable reduction of hydrocarbon fluid drag on the rotating sucker rods.

The minimal or optimal mechanical effects and advantages achieved by the method of the present invention may be calculated by, and are dependant upon the volume of compressed gas being fed into the lower end of the subsurface hydrocarbon production tubing string. By sufficiently increasing the volume of compressed gas being fed into the lower end of the subsurface hydrocarbon production tubing string at a point in proximity to, or above the subsurface production pump, the subsurface production pump output of hydrocarbon fluid and earthen contaminants combine with, and become part of, the resulting high velocity hydrocarbon fluid and gas stream flowing through the subsurface hydrocarbon production tubing string, through the wellhead, into and through the surface flow line and into the hydrocarbon production storage tank or other handling facility(s) at surface. When thus displacing the hydrocarbon fluid and it's contaminants from the output end the subsurface production pump to surface storage, all components of this hydrocarbon production pumping method and apparatus operate within a state of it's best mechanical efficiency. Herein, less horsepower is required, less equipment stress and wear is present, and the subsurface production pump operates at maximum efficiency with minimal effort and wear.

In carrying out the present invention, any desired mixture of gases, or any practical gas of convenience such as steam, natural gas, air, or carbon dioxide, may be compressed and employed as the compressed gas of choice.

The subsurface compressed gas feed tubing string and the subsurface hydrocarbon production tubing string may be suspended from or through the wellhead parallel to each other within the well bore, or one of the subsurface tubing strings may be more conveniently placed inside the other and one tubing string can exit the wellhead through a metal connector or suitable pack-off to simplify installation. By employing a hollow sucker rod string, the said hollow sucker rod string may also serve as the subsurface hydrocarbon production tubing string or as the subsurface compressed gas feed tubing string.

The greater amount of gas may be removed from the hydrocarbon fluid as the hydrocarbon fluid is fed into the hydrocarbon production fluid storage tank. The optional gas separation conduit illustrated in FIG. 3, preferably should have an inside diameter of sufficient size to conduct the hydrocarbon fluid, by gravity means, to a lower level of the hydrocarbon production fluid storage tank without having excessive spillage of hydrocarbon fluid out the top of the gas separation conduit. In selecting the inside diameter of the gas separation conduit, consideration should be given to the hydrocarbon fluid's expected input volume, temperature and viscosity.

In cases where two or more oil wells are closely positioned, as on a pad with multiple oil wells, one gas compressor of sufficient capacity may be very efficiently used to supply the compressed gas feed for two or more oil wells. With the subsurface production pump of each oil well operating continuously, the one gas compressor of sufficient capacity may inject sufficient amounts of compressed gas into the lower ends of two or more subsurface hydrocarbon production fluid columns intermittently to achieve the desired effect(s) within each oil well. A programmable valve controller or other means may be used to open and close valves as required to repetitively cycle compressed gas to each of the oil wells as required. Alternatively, the gas compressor may feed two or more oil wells simultaneously by employing compressed gas flow dividers or other means to direct accurate volumes of compressed gas to each oil well.

FIG. 2 illustrates the apparatus of the present invention wherein the sucker rods also serve as the subsurface hydrocarbon production tubing string, employing a plunger type subsurface production pump which expels it's hydrocarbon fluid output directly into the lower end of the subsurface hydrocarbon production tubing string. If an alternate choice of subsurface production pump is configured quite differently, it may be necessary to install the alternate subsurface production pump so as to expel it's hydrocarbon fluid output firstly into the subsurface compressed gas feed tubing string, and then permit the hydrocarbon fluid output to flow into the subsurface hydrocarbon production tubing string through compressed gas communication port 18.

The preferred choice of subsurface production pump for the method of the present invention is the tubing liner plunger pump. By comparison, it is much less expensive, much more durable, has a greatly extended service life, and may be used for cold primary or thermally stimulated production. If progressing cavity pumps are used, the number of progressing cavity stages should be reduced in order to make the passing of earthen solids less damaging to the rotors and stators.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus generally described the invention, reference will now be made to the accompanying drawings illustrating preferred embodiments in which;

FIG. 1 is a schematic illustration of a typical prior art system to displace hydrocarbon fluid from a subterranean hydrocarbon reservoir to surface storage or handling facility(s).

FIG. 2 is a schematic illustration outlining the method of the present invention to displace hydrocarbon fluid from a subterranean hydrocarbon reservoir to surface storage or handling facility(s).

FIG. 3 illustrates one simple method to separate gas from hydrocarbon fluid.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIG. 1, a typical conventional oil well system includes a production casing indicated by reference numeral 8 which is placed into the earth. Within the casing 8 there is provided a subsurface production tubing string 12 which is basically a length of coiled tubing or lengths of conduit coupled together from a connection from wellhead 6 to subsurface production pump 17. The system may also include what is commonly known as sucker rods 10. In use, hydrocarbon fluid 13 is fed by means of subterranean hydrocarbon reservoir 16 pressure into well bore 9 through casing perforations 14 and pumped from well bore 9 by subsurface production pump 17, into and through subsurface hydrocarbon production tubing 12, into and through wellhead 6, into and through surface flow line 21, into and through optional surface check valve 20 and into hydrocarbon production fluid storage tank 22. Valve 7 is provided to vent casing gas. Optional surface check valve 20 may be provided to prevent stored hydrocarbon fluid 13 from back-flowing from hydrocarbon production fluid storage tank 22 into subsurface hydrocarbon production tubing string 12. Vent 23 is provided to vent gas from storage tank 22. The sucker rod drive at surface is not shown.

According to the present invention, as illustrated in FIG. 2, the conventional oil well production system is modified to displace hydrocarbon fluid from an oil well's subterranean hydrocarbon reservoir to a hydrocarbon production fluid storage tank or other handling facilities at surface by following the steps of;

providing a compressed gas conveyance tubing system extending from a source of compressed gas at ground surface, through the wellhead and down the well bore to the subterranean hydrocarbon reservoir depth and returning up out of the well bore, through the wellhead and into the hydrocarbon production fluid storage tank at surface, with said compressed gas conveyance tubing system including;

a source of compressed gas 1; conduit 2; wellhead 6; casing gas vent 7; casing 8; well bore 9; subsurface compressed gas feed tubing string 11; subsurface hydrocarbon production tubing string 12; hydrocarbon fluid 13; casing perforations 14; subterranean hydrocarbon reservoir 16; subsurface production pump 17; compressed gas communication port 18; optional surface check valve 20; surface flow line 21; hydrocarbon production fluid storage tank 22; storage tank gas vent 23; optional gas separation conduit 24; gap 25;

flooding hydrocarbon fluid 13 from subterranean hydrocarbon reservoir 16 through casing perforations 14 into well bore 9, by means of subterranean hydrocarbon reservoir 16 pressure; pumping hydrocarbon production fluid 13 from well bore 9 by means of subsurface production pump 17, into and through subsurface hydrocarbon production tubing string 12, through wellhead 6, into and through surface flow line 21, into and through optional gas separation conduit 24 if it is employed, and into hydrocarbon production fluid storage tank 22;

feeding compressed gas 1 from a source at surface, into and through conduit 2, into and through wellhead 6, into and through subsurface compressed gas feed tubing string 11, into and through compressed gas communication port 18, into and through subsurface hydrocarbon production tubing string 12, through wellhead 6, into and through surface flow line 21, into and through optional gas separation conduit 24 if it is employed, and into hydrocarbon production fluid storage tank 22;

permitting the compressed gas 1 to mix with hydrocarbon production fluid 13, within subsurface hydrocarbon production tubing string 12, and achieve all possible decompression therein; permitting the resulting elevated stream velocity of the combined cubic volumes of decompressing gas, hydrocarbon fluid and contaminants, to flow through subsurface hydrocarbon production tubing string 12, through wellhead 6, into and through surface flow line 21, into and through optional gas separation conduit 24 if it is employed, and into hydrocarbon production fluid storage tank 22;

causing the high density of the column of hydrocarbon fluid 13, flowing through subsurface hydrocarbon production tubing string 12, to be reduced to a choice of any desired density during and throughout normal operating time, by supplying and mixing the volume of gas 1 as required, into the column of hydrocarbon fluid 13;

optionally separating the mixture of compressed gas 1 and hydrocarbon fluid 13 by feeding hydrocarbon fluid 13 from the output end of conduit 21, through gap 25, into the open top end of and through optional gas separation conduit 24;

venting gas 1 from hydrocarbon production fluid storage tank 22, through storage tank gas vent 23 to atmosphere or other gas handling facility; optionally preventing stored hydrocarbon fluid 13 from back-flowing from hydrocarbon production fluid storage tank 22 into subsurface production tubing string 12 by means of optional surface check valve 20; operating the hydrocarbon production system; recovering hydrocarbon fluid 13 and contaminants from the hydrocarbon production fluid storage tank 22 or other handling facility(s). 

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
 1. A method of displacing light, medium or very viscose hydrocarbon fluid which may contain solid earthen contaminants and water, from the subterranean hydrocarbon reservoir of an oil well to a hydrocarbon production fluid storage tank or other handling facilities at ground surface, by means of an oil well, a compressed gas conveyance tubing system and a subsurface production pump, comprising the steps of; constructing a compressed gas conveyance tubing system extending from a source of compressed gas at surface, through the wellhead and down the well bore to the approximate subterranean hydrocarbon reservoir depth of the well bore and returning up out of the well bore, through the wellhead and into a hydrocarbon production fluid storage tank or other handling facilities at ground surface; connecting a subsurface production pump to the lower end of the compressed gas conveyance tubing system, including means to activate said subsurface production pump; flooding hydrocarbon fluid from the subterranean hydrocarbon reservoir by means of subterranean hydrocarbon reservoir pressure, through the casing perforations and into the well bore; pumping hydrocarbon fluid from the well bore into and through the subsurface hydrocarbon production tubing string, wellhead and surface flow line, and into the hydrocarbon fluid storage tank or other handling facilities at surface; feeding a sufficient volume and pressure of compressed gas from a source at surface, through the compressed gas conveyance tubing system, and into the hydrocarbon fluid storage tank or other handling facilities at surface; separating gas and hydrocarbon fluid therein; venting gas from the hydrocarbon production fluid storage tank or other handling facilities; continuing the hydrocarbon production system's production cycle; recovering hydrocarbon fluid and contaminants from the hydrocarbon production fluid storage tank or other facilities at ground surface.
 2. A method of significantly reducing the operating load upon the subsurface production pump and prime mover, comprising the steps of; providing the apparatus and method of claim 1; ensuring that the compressed gas fed and mixed into the hydrocarbon fluid column flowing to surface storage through the subsurface hydrocarbon production tubing string and surface flow line is of sufficient volume to decompress and expand therein, to a degree that sufficiently displaces and reduces the density of the said hydrocarbon fluid column above the subsurface production pump.
 3. A method of significantly decreasing the sucker rod fall time of subsurface reciprocating plunger pumps, comprising the steps of; providing the method and apparatus of claim 1; ensuring that the compressed gas fed and mixed into the hydrocarbon fluid column flowing to surface storage through the subsurface hydrocarbon production tubing string and surface flow line is of sufficient volume to decompress and expand therein, to a degree that sufficiently displaces and reduces the density of the said hydrocarbon fluid column, as to permit unimpeded lowering of the sucker rods and subsurface pump plunger through the said hydrocarbon fluid column.
 4. A method to eliminate the precipitation and accumulation of earthen particulates or small rocks or sharp edged rock fragments or pyrite balls within the subsurface production tubing string and surface flow line, while displacing hydrocarbon fluid containing such earthen contaminants from the output end of the subsurface production pump of an oil well to a hydrocarbon production fluid storage tank or other handling facilities at ground surface, comprising the steps of; providing the apparatus and method of claim 1; ensuring that the compressed gas fed and mixed into the hydrocarbon fluid column flowing to surface storage through the subsurface hydrocarbon production tubing string and surface flow line is of sufficient volume and pressure to permit the resulting enhanced velocity of the stream of combined cubic volumes of hydrocarbon fluid, earthen contaminants and decompressed gas, to flow from the subsurface production pump to the hydrocarbon production fluid storage tank or other handling facilities at surface.
 5. A method to significantly reduce premature wear and failure of progressing cavity subsurface production pumps caused by pumping high hydrocarbon fluid pressures, or by pumping hydrocarbon fluid containing earthen particulates or small rocks, while displacing hydrocarbon fluid containing such earthen contaminants from the subterranean hydrocarbon reservoir of an oil well to a hydrocarbon production fluid storage tank or other handling facilities at ground surface, comprising the steps of; providing the apparatus and method of Claim
 2. 